Materials and Methods
We randomized 18 men with prostate cancer who did not receive prior therapy to a low fat (15% kcal), high fiber, soy protein supplemented diet or a Western (40% kcal fat) diet for 4 weeks. Fasting serum was collected at baseline and after the intervention to measure prostate specific antigen, sex hormones, insulin, insulin-like growth factor I and II, insulin-like growth factor binding proteins, lipids and fatty acids. LNCaP cells (ATCC®) were cultured in medium containing pre-intervention and post-intervention human serum to assess the in vitro effect of the diet on prostate cancer cell proliferation.
Results
Subjects in each group were highly compliant with the dietary intervention. Serum from men in the low fat group significantly decreased the growth of LNCaP cells relative to Western diet serum (p = 0.03). There were no significant between group changes in serum prostate specific antigen, sex hormones, insulin, insulin-like growth factor I and II, and insulin-like growth factor binding proteins. Serum triglyceride and linoleic acid (ω-6) levels were decreased in the low fat group (p = 0.034 and 0.005, respectively). Correlation analysis revealed that decreased ω-6 and increased ω-3 fatty acid correlated with decreased serum stimulated LNCaP cell growth (r = 0.64, p = 0.004 and r = −0.49, p = 0.04, respectively).
Conclusions
In this prospective, randomized dietary intervention trial a low fat diet resulted in changes in serum fatty acid levels that were associated with decreased human LNCaP cancer cell growth. Further prospective trials are indicated to evaluate the potential of low fat diets for prostate cancer prevention and treatment.
Key Words: prostate; prostatic neoplasms; dietary fats; fatty acids; ω-6
Abbreviations: BMI, body mass index; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; IGF, insulin-like growth factor; IGFBP, IGF binding protein; PSA, prostate specific antigen
William J. Aronsona, b, , , R. James Barnard†, h, Stephen J. Freedlandi, Susanne Henninge, David Elashoffc, Patricia M. Jardackg, Pinchas Cohend, f, David Hebere and Naoko Kobayashib
aUrology Section, Department of Surgery, Veterans Administration, Greater Los Angeles Healthcare System
bDepartment of Urology, University of California-Los Angeles, Los Angeles, California
cDepartment of Biostatistics, University of California-Los Angeles, Los Angeles, California
dDepartment of Pediatrics, University of California-Los Angeles, Los Angeles, California
eDivision of Clinical Nutrition, University of California-Los Angeles, Los Angeles, California
fDivision of Pediatric Endocrinology, University of California-Los Angeles, Los Angeles, California
gDivision of General Clinical Research Center, School of Medicine, University of California-Los Angeles, Los Angeles, California
hDepartment of Physiological Sciences, University of California-Los Angeles, Los Angeles, California
iDepartment of Surgery, Durham Veterans Affairs Medical Center and Division of Urologic Surgery and Duke Prostate Center, Departments of Surgery and Pathology, Duke University Medical Center, Durham, North Carolina